Pattern of electrodes for a touch sensor

ABSTRACT

In certain embodiments, a touch sensor includes first, second, and third electrode tracks. The first electrode track includes a first electrode, which has a first segment, a second segment connected to the first segment, and a third segment connected to the first segment. The second electrode track includes a second electrode, which includes a fourth segment, a fifth segment connected to the fourth segment, and a sixth segment connected to the fourth segment. A portion of the second segment extends between portions of the fifth and sixth segments from a perspective orthogonal to the surface of the touch sensor, and a portion of the fifth segment extends between portions of the second and third segments from the orthogonal perspective. The third electrode track includes a third electrode, a portion of which extends between portions of the first and second electrodes from the orthogonal perspective.

TECHNICAL FIELD

This disclosure generally relates to touch sensors; and moreparticularly to patterns of electrodes for a touch sensor.

BACKGROUND

A touch sensor may detect the presence and location of a touch or theproximity of an object (such as a user's finger or a stylus) within atouch-sensitive area of the touch sensor overlaid on a display screen,for example. In a touch-sensitive-display application, the touch sensormay enable a user to interact directly with what is displayed on thescreen, rather than indirectly with a mouse or touch pad. A touch sensormay be attached to or provided as part of a desktop computer, laptopcomputer, tablet computer, personal digital assistant (PDA), smartphone,satellite navigation device, portable media player, portable gameconsole, kiosk computer, point-of-sale device, or other suitable device.A control panel on a household or other appliance may include a touchsensor.

There are a number of different types of touch sensors, such as (forexample) resistive touch screens, surface acoustic wave touch screens,and capacitive touch screens. Herein, reference to a touch sensor mayencompass a touch screen, and vice versa, where appropriate. When anobject touches or comes within proximity of the surface of thecapacitive touch screen, a change in capacitance may occur within thetouch screen at the location of the touch or proximity. A touch-sensorcontroller may process the change in capacitance to determine theposition of the change in capacitance on the touch screen.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example touch sensor with an example touch-sensorcontroller that may be used in certain embodiments of the presentdisclosure.

FIG. 2 illustrates an example device and example electrodes that may beused in certain embodiments of the present disclosure.

FIG. 3A illustrates an example series of electrodes that may be used incertain embodiments of a touch sensor.

FIG. 3B illustrates an example electrode that may be used in certainembodiments of a touch sensor.

FIG. 4 illustrate an example capacitive node that may be used in certainembodiments of a touch sensor.

FIG. 5A illustrates example touch points on an example touch sensor.

FIG. 5B illustrates a graph of example measurements that may be taken bycertain embodiments of a touch sensor.

FIG. 5C illustrates a graph of example measurements and noise effectsthat may be measured by certain embodiments of a touch sensor.

FIG. 6A illustrates example test drawings that may be registered bycertain embodiments of a touch sensor.

FIG. 6B illustrates example test drawings that may be registered by analternative embodiment of a touch sensor.

The drawings included in the Figures are not drawn to scale.

DESCRIPTION OF EXAMPLE EMBODIMENTS

FIG. 1 illustrates an example touch sensor 10 with an exampletouch-sensor controller 12, according to certain embodiments of thepresent disclosure. Touch sensor 10 and touch-sensor controller 12 maydetect the presence and location of a touch or the proximity of anobject within a touch-sensitive area of touch sensor 10. Herein,reference to a touch sensor may encompass both the touch sensor and itstouch-sensor controller, where appropriate. Similarly, reference to atouch-sensor controller may encompass both the touch-sensor controllerand its touch sensor, where appropriate. Touch sensor 10 may include oneor more touch-sensitive areas, where appropriate. Touch sensor 10 mayinclude an array of drive and sense electrodes (or an array ofelectrodes of a single type) disposed on one or more substrates, whichmay be made of a dielectric material. Herein, reference to a touchsensor may encompass both the electrodes of the touch sensor and thesubstrate(s) that they are disposed on, where appropriate.Alternatively, where appropriate, reference to a touch sensor mayencompass the electrodes of the touch sensor, but not the substrate(s)that they are disposed on.

An electrode (whether a ground electrode, a guard electrode, a driveelectrode, or a sense electrode) may be an area of conductive materialforming a shape, such as for example a disc, square, rectangle, thinline, other suitable shape, or suitable combination of these. One ormore cuts in one or more layers of conductive material may (at least inpart) create the shape of an electrode, and the area of the shape may(at least in part) be bounded by those cuts. In particular embodiments,the conductive material of an electrode may occupy approximately 100% ofthe area of its shape. As an example and not by way of limitation, anelectrode may be made of indium tin oxide (ITO) and the ITO of theelectrode may occupy approximately 100% of the area of its shape(sometimes referred to as 100% fill), where appropriate. In particularembodiments, the conductive material of an electrode may occupysubstantially less than 100% of the area of its shape. As an example andnot by way of limitation, an electrode may be made of fine lines ofmetal or other conductive material (FLM), such as for example copper,silver, or a copper- or silver-based material, and the fine lines ofconductive material may occupy approximately 5% of the area of its shapein a hatched, mesh, or other suitable pattern. Herein, reference to FLMencompasses such material, where appropriate.

Where appropriate, the shapes of the electrodes (or other elements) of atouch sensor may constitute in whole or in part one or moremacro-features of the touch sensor. One or more characteristics of theimplementation of those shapes (such as, for example, the conductivematerials, fills, or patterns within the shapes) may constitute in wholeor in part one or more micro-features of the touch sensor. One or moremacro-features of a touch sensor may determine one or morecharacteristics of its functionality, and one or more micro-features ofthe touch sensor may determine one or more optical features of the touchsensor, such as transmittance, refraction, or reflection.

A mechanical stack may contain the substrate (or multiple substrates)and the conductive material forming the drive or sense electrodes oftouch sensor 10. As an example and not by way of limitation, themechanical stack may include a first layer of optically clear adhesive(OCA) beneath a cover panel. The cover panel may be clear and made of aresilient material suitable for repeated touching, such as for exampleglass, polycarbonate, or poly(methyl methacrylate) (PMMA). Thisdisclosure contemplates any suitable cover panel made of any suitablematerial. The first layer of OCA may be disposed between the cover paneland the substrate with the conductive material forming the drive orsense electrodes. The mechanical stack may also include a second layerof OCA and a dielectric layer (which may be made of PET or anothersuitable material, similar to the substrate with the conductive materialforming the drive or sense electrodes). As an alternative, whereappropriate, a thin coating of a dielectric material may be appliedinstead of the second layer of OCA and the dielectric layer. The secondlayer of OCA may be disposed between the substrate with the conductivematerial making up the drive or sense electrodes and the dielectriclayer, and the dielectric layer may be disposed between the second layerof OCA and an air gap to a display of a device including touch sensor 10and touch-sensor controller 12. As an example only and not by way oflimitation, the cover panel may have a thickness of approximately 1 mm;the first layer of OCA may have a thickness of approximately 0.05 mm;the substrate with the conductive material forming the drive or senseelectrodes may have a thickness of approximately 0.05 mm; the secondlayer of OCA may have a thickness of approximately 0.05 mm; and thedielectric layer may have a thickness of approximately 0.05 mm. Althoughthis disclosure describes a particular mechanical stack with aparticular number of particular layers made of particular materials andhaving particular thicknesses, this disclosure contemplates any suitablemechanical stack with any suitable number of any suitable layers made ofany suitable materials and having any suitable thicknesses. As anexample and not by way of limitation, in particular embodiments, a layerof adhesive or dielectric may replace the dielectric layer, second layerof OCA, and air gap described above, with there being no air gap to thedisplay.

One or more portions of the substrate of touch sensor 10 may be made ofpolyethylene terephthalate (PET) or another suitable material. Thisdisclosure contemplates any suitable substrate with any suitableportions made of any suitable material. In particular embodiments, thedrive or sense electrodes in touch sensor 10 may be made of ITO in wholeor in part. In particular embodiments, the drive or sense electrodes intouch sensor 10 may be made of fine lines of metal or other conductivematerial. As an example and not by way of limitation, one or moreportions of the conductive material may be copper or copper-based andhave a thickness of approximately 5 μm or less and a width ofapproximately 10 μm or less. As another example, one or more portions ofthe conductive material may be silver or silver-based and similarly havea thickness of approximately 5 μm or less and a width of approximately10 μm or less. This disclosure contemplates electrodes made of anysuitable material.

Touch sensor 10 may implement a capacitive form of touch sensing. In amutual-capacitance implementation, touch sensor 10 may include an arrayof drive and sense electrodes forming an array of capacitive nodes. Adrive electrode and a sense electrode may form a capacitive node. Thedrive and sense electrodes forming the capacitive node may come neareach other, but not make electrical contact with each other. Instead,the drive and sense electrodes may be capacitively coupled to each otheracross a space between them. A pulsed or alternating voltage applied tothe drive electrode (by touch-sensor controller 12) may induce a chargeon the sense electrode, and the amount of charge induced may besusceptible to external influence (such as a touch or the proximity ofan object). When an object touches or comes within proximity of thecapacitive node, a change in capacitance may occur at the capacitivenode and touch-sensor controller 12 may measure the change incapacitance. A touch may refer to an external object touching acapacitive node directly or touching a cover or substrate adjacent tothe capacitive node. By measuring changes in capacitance throughout thearray, touch-sensor controller 12 may determine the position of thetouch or proximity within the touch-sensitive area(s) of touch sensor10.

In a self-capacitance implementation, touch sensor 10 may include anarray of electrodes of a single type that may each form a capacitivenode. When an object touches or comes within proximity of the capacitivenode, a change in self capacitance may occur at the capacitive node andtouch-sensor controller 12 may measure the change in capacitance, forexample, as a change in the amount of charge needed to raise the voltageat the capacitive node by a pre-determined amount. As with amutual-capacitance implementation, by measuring changes in capacitancethroughout the array, touch-sensor controller 12 may determine theposition of the touch or proximity within the touch-sensitive area(s) oftouch sensor 10. This disclosure contemplates any suitable form ofcapacitive touch sensing, where appropriate.

In particular embodiments, one or more drive electrodes may togetherform a drive line running horizontally or vertically or in any suitableorientation. Similarly, one or more sense electrodes may together form asense line running horizontally or vertically or in any suitableorientation. In particular embodiments, drive lines may runsubstantially perpendicular to sense lines. Herein, reference to a driveline may encompass one or more drive electrodes making up the driveline, and vice versa, where appropriate. Similarly, reference to a senseline may encompass one or more sense electrodes making up the senseline, and vice versa, where appropriate.

Touch sensor 10 may have drive and sense electrodes disposed in apattern on one side of a single substrate. In such a configuration, apair of drive and sense electrodes capacitively coupled to each otheracross a space between them may form a capacitive node. For aself-capacitance implementation, electrodes of only a single type may bedisposed in a pattern on a single substrate. In addition or as analternative to having drive and sense electrodes disposed in a patternon one side of a single substrate, touch sensor 10 may have driveelectrodes disposed in a pattern on one side of a substrate and senseelectrodes disposed in a pattern on another side of the substrate.Moreover, touch sensor 10 may have drive electrodes disposed in apattern on one side of one substrate and sense electrodes disposed in apattern on one side of another substrate. In such configurations, anintersection of a drive electrode and a sense electrode may form acapacitive node. Such an intersection may be a location where the driveelectrode and the sense electrode “cross” or come nearest each other intheir respective planes. The drive and sense electrodes do not makeelectrical contact with each other—instead they are capacitively coupledto each other across a dielectric at the intersection. In someembodiments, this dielectric may be air. Moreover, this disclosurecontemplates electrodes disposed on any suitable number of substrates.

As described above, a change in capacitance at a capacitive node oftouch sensor 10 may indicate a touch or proximity input at the positionof the capacitive node. Touch-sensor controller 12 may detect andprocess the change in capacitance to determine the presence and locationof the touch or proximity input. Touch-sensor controller 12 may thencommunicate information about the touch or proximity input to one ormore other components (such one or more central processing units (CPUs))of a device that includes touch sensor 10 and touch-sensor controller12, which may respond to the touch or proximity input by initiating afunction of the device (or an application running on the device).Although this disclosure describes a particular touch-sensor controllerhaving particular functionality with respect to a particular device anda particular touch sensor, this disclosure contemplates any suitabletouch-sensor controller having any suitable functionality with respectto any suitable device and any suitable touch sensor.

Touch-sensor controller 12 may be one or more integrated circuits (ICs),such as for example general-purpose microprocessors, microcontrollers,programmable logic devices or arrays, application-specific ICs (ASICs).In particular embodiments, touch-sensor controller 12 comprises analogcircuitry, digital logic, and digital non-volatile memory. In particularembodiments, touch-sensor controller 12 is disposed on a flexibleprinted circuit (FPC) bonded to the substrate of touch sensor 10, asdescribed below. The FPC may be active or passive, where appropriate. Inparticular embodiments, multiple touch-sensor controllers 12 aredisposed on the FPC. Touch-sensor controller 12 may include a processorunit, a drive unit, a sense unit, and a storage unit. The drive unit maysupply drive signals to the drive electrodes of touch sensor 10. Thesense unit may sense charge at the capacitive nodes of touch sensor 10and provide measurement signals to the processor unit representingcapacitances at the capacitive nodes. The processor unit may control thesupply of drive signals to the drive electrodes by the drive unit andprocess measurement signals from the sense unit to detect and processthe presence and location of a touch or proximity input within thetouch-sensitive area(s) of touch sensor 10. The processor unit may alsotrack changes in the position of as touch or proximity input within thetouch-sensitive areas) of touch sensor 10. The storage unit may storeprogramming for execution by the processor unit, including programmingfor controlling the drive unit to supply drive signals to the driveelectrodes, programming for processing measurement signals from thesense unit, and other suitable programming, where appropriate. Althoughthis disclosure describes a particular touch-sensor controller having aparticular implementation with particular components, this disclosurecontemplates any suitable touch-sensor controller having any suitableimplementation with any suitable components.

Tracks 14 of conductive material disposed on the substrate of touchsensor 10 may couple the drive or sense electrodes of touch sensor 10 toconnection pads 16, also disposed on the substrate of touch sensor 10.As described below, connection pads 16 facilitate coupling of tracks 14to touch-sensor controller 12. Tracks 14 may extend into or around (e.g.at the edges of) the touch-sensitive area(s) of touch sensor 10.Particular tracks 14 may provide drive connections for couplingtouch-sensor controller 12 to drive electrodes of touch sensor 10,through with the drive unit of touch-sensor controller 12 may supplydrive signals to the drive electrodes. Other tracks 14 may provide senseconnections for coupling touch-sensor controller 12 to sense electrodesof touch sensor 10, through which the sense unit of touch-sensorcontroller 12 may sense charge at the capacitive nodes of touch sensor10. Tracks 14 may be made of fine lines of metal or other conductivematerial. As an example and not by way of limitation, the conductivematerial of tracks 14 may be copper or copper-based and have a width ofapproximately 100 μm or less. As another example, the conductivematerial of tracks 14 may be silver or silver-based and have a width ofapproximately 100 μm or less. In particular embodiments, tracks 14 maybe made of ITO in whole or in part in addition or as an alternative tofine lines of metal or other conductive material. Although thisdisclosure describes particular tracks made of particular materials withparticular widths, this disclosure contemplates any suitable tracks madeof any suitable materials with any suitable widths. In addition totracks 14, touch sensor 10 may include one or more ground linesterminating at a ground connector (which may be a connection pad 16) atan edge of the substrate of touch sensor 10 (similar to tracks 14).

Connection pads 16 may be located along one or more edges of thesubstrate, outside the touch-sensitive area(s) of touch sensor 10. Asdescribed above, touch-sensor controller 12 may be on an FPC. Connectionpads 16 may be made of the same material as tracks 14 and may be bondedto the FPC using an anisotropic conductive film (ACF). Connection 18 mayinclude conductive lines on the FPC coupling touch-sensor controller 12to connection pads 16, in turn coupling touch-sensor controller 12 totracks 14 and to the drive or sense electrodes of touch sensor 10. Inanother embodiment, connection pads 16 may be connected to anelectro-mechanical connector (such as a zero insertion threewire-to-board connector); in this embodiment, connection 18 may not needto include an FPC. This disclosure contemplates any suitable connection18 between touch-sensor controller 12 and touch sensor 10.

Certain embodiments of touch sensor 10 and touch-sensor controller 12may measure capacitance or a change in capacitance using any suitablemethod. For example, voltage may be applied to one or more tracks 14 byopening or closing one or more switches associated with one or moretracks 14. Such switches may connect one or more tracks 14 to otherportions of touch sensor 10 or touch-sensor controller 12 such as, forexample, a voltage supply rail, ground, virtual ground, and/or any othersuitable component. Such methods may cause charge to be transferred toor from one or more portions of tracks 14 (e.g., one or more drivelines), which may induce a corresponding transfer of charge on one ormore portions of one or more other tracks 14 (e.g., one or more senselines). The presence of an object such as a finger or a stylus maychange the amount of charge induced on the sensed track 14, and thischange may be measured by touch-controller 12 to determine the positionof the object.

Certain embodiments may perform measurements using any suitable numberof steps that facilitate capacitance measurements. For example, someembodiments may perform any suitable combination of pre-charging one ormore tracks 14, charging one or more tracks 14, transferring chargebetween two or more tracks 14, discharging one or more tracks 14, and/orany other suitable step. In some embodiments, a transfer of charge maybe measured directly or indirectly. For example, certain embodiments mayutilize voltage measurements, current measurements, timing measurements,any other suitable measurement, or any combination thereof to measurecapacitance or a change in capacitance at one or more capacitive nodes16. Furthermore, certain embodiments may utilize additional circuitry(such as, for example, one or more integrators, amplifiers, capacitors,switches, audio-to-digital converters, and/or any other suitablecircuitry) to perform and/or enhance such measurements. Certainembodiments may measure a value at a particular point in time, measure achange in a value over time, and/or perform any other suitableprocessing to facilitate the determination of an object's positionrelative to touch sensor 10.

FIG. 2 illustrates an example device 20 and example electrode tracks 14that may be used in certain embodiments of the present disclosure. Inthe illustrated embodiment, device 20 includes touch screen 10, whichincludes vertical tracks 14 a and horizontal tracks 14 b.

Device 20 may be any touch-sensing device or component. In variousembodiments, device 20 may be a smart phone, tablet computer, laptopcomputer, or any suitable device utilizing a touch sensor 10. Device 20may include a display 21 that may be overlaid by or otherwise positionedproximate to touch sensor 10. Display 21 and touch sensor 10 may besubstantially planar, curved, or have any other suitable configuration.

Tracks 14 a may include any structure, configuration, and/or functiondescribed above with respect to FIG. 1. In the illustrated embodiment,each track 14 a includes a series of conductively connected electrodes22 running vertically across display 21. Alternative embodiments mayhave series of electrodes 22 running horizontally or in any othersuitable configuration. One or more tracks 14 a may have voltage appliedby touch-sensor controller 12 to perform touch-sensing. One or moretracks 14 a may operate as a drive line or as a sense line to performmutual capacitance sensing. One or more tracks 14 a may also be used toperform other sensing methods based on the configuration of touch-sensorcontroller 12. Tracks 14 a are described in further detail below withrespect to FIG. 3A.

Tracks 14 b may include any structure, configuration, and/or functiondescribed above with respect to FIG. 1. In the illustrated embodiment,each track 14 b includes a single electrode 24 running horizontallyacross display 21. Alternative embodiments may have electrodes 24running vertically or in any other suitable configuration. One or moretracks 14 b may have voltage applied it by touch-sensor controller 12 toperform touch-sensing. One or more tracks 14 b may operate as a driveline or as a sense line to perform mutual capacitance sensing. One ormore tracks 14 b may also used to perform other sensing methods based onthe configuration of touch-sensor controller 12. Tracks 14 b aredescribed in further detail below with respect to FIG. 3B.

Electrodes 22 may be any component operable to conduct electricity tofacilitate touch-sensing. Electrodes 22 may be composed of ITO, metal orany other suitable conductive material, or any suitable combinationthereof. In the illustrated embodiment, each electrode 22 is formedapproximately in the shape of a capital “F”, and portions of eachelectrode 22 interleave with portions of an electrode 22 of an adjacenttrack 14. Other embodiments may utilize different shapes and/or sizes,as discussed in further detail below with respect to FIG. 3A. Suchconfiguration may increase the amount of surface area on touch sensor 10where drive and sense electrodes are positioned close to one another,which may improve the precision and/or linearity of touch-sensingoperations.

Electrodes 24 may be any component operable to conduct electricity tofacilitate touch-sensing. Electrodes 24 may be composed of ITO, metal orany other suitable conductive material, or any suitable combinationthereof. In the illustrated embodiment, each electrode 24 crosses tracks14 a and surrounds (from a perspective orthogonal to the surface oftouch sensor 10) an electrode 22 from each track 14 a. Portions ofelectrode 24 may also pass between the interleaved segments of adjacentelectrodes 22. Other embodiments may utilize different shapes and/orsizes, as discussed in further detail below with respect to FIG. 3B. Inembodiments where one or more tracks 14 a are driven while one or moretracks 14 b are sensed, or vice versa, this configuration may increasethe amount of surface area on touch sensor 10 where drive and senseelectrodes are positioned close to one another, which may improve theprecision and/or linearity of touch-sensing operations.

FIG. 3A illustrates an example electrode track 14 a that may be used incertain embodiments of a touch sensor 10. In the illustrated embodiment,electrode track 14 a includes a series of electrodes 22 and conductivebridges 32. While track 14 a is depicted as having a particularconfiguration of electrodes 22 and conductive bridges 32, any suitableconfiguration may be used. For example, each electrode 22 may be furtherbroken down into two or more electrodes that are connected by anotherconductive bridge 32. As another example, electrodes 22 may be formed asa single continuous electrode rather than as separate electrodes 22connected by conductive bridges 32.

Electrodes 22 may have any structure, configuration, and/or functiondescribed above with respect to FIG. 2. Because each electrode 22 isgalvanically connected by a conductive bridge 32, applying voltage toany portion of track 14 a may result in charging of each electrode 22.In the illustrated embodiment, each electrode 22 includes segments 26,28, and 30. Segment 26 runs in the direction of the longitudinal axis oftrack 14 a while segments 28 and 30 extend perpendicular to segment 26.The extension of segments 28 and 30 may increase the surface area wheredrive and sense electrodes are adjacent to one another, which mayimprove the precision and/or linearity of touch sensing. Furthermore,segments 28 and 30 may interleave with segments 28 and 30 of electrodes22 of an adjacent track 14 a (not shown in FIG. 3A), which may reducethe occurrence of low-sensitivity zones between adjacent capacitivenodes in certain embodiments. Segments 26, 28, and 30 may be anysuitable length and width. In a particular embodiment, segments 26, 28,and 30 may have lengths of 3.8 mm, 2.3 mm, and 2.3 mm, respectively. Inan alternative embodiment, segments 26, 28, and 30 may have lengths of1.9 mm, 1.2 mm, and 1.2 mm, respectively. In other embodiments, segment26 may be between 1.75 mm and 6 mm. Furthermore, in certain embodimentssegments 28 and 30 may have the same length or different lengths.

FIG. 3B illustrates an example electrode track 14 b that may be used incertain embodiments of a touch sensor 10. In the illustrated embodiment,electrode track 14 b includes electrode 24. While track 14 b is depictedas using a particular configuration of electrode 24, any suitableconfiguration may be used. For example, in embodiments where electrodes22 are not formed approximately in the shape of a capital “F”, electrode24 may be formed in any suitable shape to accommodate the shape ofelectrodes 22. As another example, some embodiments may use a series ofelectrodes 24 connected by a conductive bridge rather than a single,continuous electrode 24.

Electrode 24 may have any structure, configuration, and/or functiondescribed above with respect to FIG. 2. Electrode 24 may be formed tofit around one or more electrodes 22 (see, e.g., FIG. 4). Thisconfiguration may increase the surface area where sense and driveelectrodes are adjacent to one another, which may improve the precisionand/or linearity of touch sensing by reducing the area of touch sensor10 where there is relatively low sensitivity. Such sensing improvementsmay be especially important when the external object whose position isbeing detected is relatively small compared to the size of thecapacitive nodes of touch-sensor 10. For example, the precision and/orlinearity of detecting the position of a stylus may be particularlyimproved where the tip of the stylus has a circumference that is smallerthan the capacitive nodes of touch sensor 10. Such technical advantagesare illustrated in further detail below with respect to FIGS. 5A-C and6A-B.

FIG. 4 illustrate an example capacitive node 34 that may be used incertain embodiments of a touch sensor 10. In the illustrated embodiment,capacitive node 34 includes electrodes 22 and 24, and capacitive node 34may be connected to other capacitive nodes 34 by conductive bridges 32.

Capacitive node 34 may be any component operable to measure a change incapacitance caused by the presence of an external object. Capacitivenode 34 may include any structure, configuration, and/or functiondescribed above with respect to FIG. 1. In the illustrated embodiment,capacitive node 34 includes electrodes 22 a, 22 b, and 24. Inalternative embodiments, capacitive node 34 may include more or fewerelectrodes, in various embodiments, one or more tracks 14 a may bedriven simultaneously and one or more tracks 14 b may be sensedsimultaneously (or vice versa), and the size, shape, and/or position ofcapacitive node 34 may be determined by the sensing operation performed.For example, in an embodiment where electrode 22 a is driven whileelectrode 24 is sensed, capacitive node 24 may correspond to the areawhere electrode 24 is adjacent to electrode 22 a. In an embodiment whereelectrodes 22 a and 22 b are both driven while electrode 24 is sensed,capacitive node 34 may correspond to full area shown in FIG. 4.Furthermore, in some embodiments, the same touch sensor 10 may utilizemultiple configurations of capacitive node 34 at different times.

Electrodes 22 a and 22 b may have any structure, configuration, and/orfunction described above with respect to electrode 22 in FIGS. 2 and 3A.Electrode 22 a includes segments 26 a, 28 a, and 30 a; and electrode 22b includes segments 26 b, 28 b, and 30 b. From a perspective orthogonalto the surface of touch sensor 10, a portion of segment 28 a extendsbetween portions of segments 28 b and 30 b. Similarly, from aperspective orthogonal to the surface of touch sensor 10, a portion ofsegment 28 b extends between portions of segments 28 a and 30 a. Thisinterleaving of electrodes 22 may reduce the occurrence oflow-sensitivity zones between adjacent electrode tracks, which mayimprove the precision and/or linearity of touch sensing operations.Segments 28 and 30 may be the same length or have different lengths.Segment 28 and/or segment 30 may be perpendicular or not perpendicularto segment 26. Furthermore, while in some embodiments, segments 26, 28,and/or 30 may be substantially straight; in other embodiments, segments26, 28, and/or 30 may contain one or more curves.

Electrode 24 may have any structure, configuration, and/or functiondescribed above with respect to electrode 24 in FIG. 2. As shown in FIG.2, certain embodiments may have a small gap between electrodes 22 and 24to facilitate capacitive coupling. This gap may simply be a spacebetween electrodes 22 and 24, or it may be partially or completelyfilled by a dielectric material, any other suitable material tofacilitate capacitive coupling, or any suitable combination thereof.Electrode 24 may partially or completely surround electrodes 22 a and 22b (from a perspective orthogonal to the surface of touch sensor 10). Byextending around and between electrodes 22 and 24, certain embodimentsmay increase the surface area of touch sensor 10 where drive and senseelectrodes are adjacent. Since such areas have increased capacitivesensitivity, such configurations may reduce the occurrence of lowsensitivity areas and/or reduce the difference between the maximumsensitivity areas and minimum sensitivity areas on touch sensor 10.

Conductive bridge 32 may have any structure, configuration, and/orfunction described above with respect to FIG. 3A. In the illustratedembodiment, conductive bridges 32 allow the electrodes 22 in a track 14a to be galvanically connected across electrodes 24 of tracks 14 b. Thisconfiguration may be used in embodiments where electrodes 22 and 24 aredisposed on the same substrate of touch sensor 10. In embodiments whereelectrodes 22 and 24 are disposed on separate substrates, conductivebridges 32 may not be used since the electrodes 22 of tracks 14 a andelectrodes 24 of tracks 14 b of such embodiments are formed on separatelayers.

FIG. 5A illustrates example touch points on an example touch sensor.Touch points 36 a-36 e depict the position of an object moving from leftto right across capacitive nodes 34 a and 34 b.

Capacitive nodes 34 a and 34 b may include one or more components oftouch sensor 10 that are operable to perform a capacitive measurement.For example, in the illustrated embodiment, capacitive node 34 aincludes electrodes 22 a, 22 b, and 24, and capacitive node 34 bincludes electrodes 22 c, 22 d, and 24. The elements making up a singlecapacitive node may be determined by which electrodes are driven andsensed at a particular time. While FIG. 5A depicts a particularconfiguration of capacitive nodes 34, any suitable configuration may beused. Capacitive measurements corresponding to capacitive nodes 34 a and34 b are shown by measurements 40 a and 40 b, respectively, in FIGS. 5Band 5C.

Touch points 36 represent a portion of an object touching or beingpositioned close to touch sensor 10 as the object moves laterally acrosstouch sensor 10. For example, touch points 36 may represent the tip of astylus or any other suitable object as it moves across capacitive nodes34 a and 34 b. The presence of the object at touch points 36 a-36 e mayresult in different capacitive measurements due to differentsensitivities of various portions of capacitive nodes 34. The change incapacitance measured by touch-sensor controller 12 (relative to thecapacitance when the object is not present) may be referred to as a“delta capacitance.” In certain embodiments, delta capacitance may be adifference or a ratio between the capacitance value measured or expectedwhen the object and not present and the capacitance value measuredduring the sensing sequence. Because the distance between the object andthe capacitive node 34 may affect the change in capacitance experiencedby the capacitive node 34, touch points 36 a-36 e may result inmeasurements having different delta capacitances. As used herein,“maximum delta” refers to the maximum delta capacitance measured as theobject moves across capacitive nodes 34, which corresponds to touchpoints 36 b and 36 d in the illustrated embodiment. As used herein,“minimum delta” refers to the minimum delta capacitance measured as theobject moves across capacitive nodes 34, which corresponds to touchpoints 36 a, 36 c, and 36 e in the illustrated embodiment. Theconfiguration of electrodes 22 and 24 may improve the sensitivity ofcertain portions touch sensor 10, which may increase the non-maximumdelta capacitance values.

FIG. 5B illustrates a graph of example measurements that may be taken bycertain embodiments of touch sensor 10. The illustrated graph depictsdelta capacitance measurements taken as an object moves across touchsensor 10. The graph includes measurements 40 a, 40 b, 42 a, and 42 b;positions 44 a-44 e; and threshold values 46 a and 46 b.

Measurements 40 a and 40 b represent delta capacitance measurementstaken as an object moves across touch sensor 10. Measurement 40 arepresents the measurement taken by capacitive node 34 a of FIG. 5A.Measurement 40 b represents the change in capacitance measured bycapacitive node 34 b of FIG. 5A. In the illustrated embodiment, thischange in capacitance is shown as a difference between amplifiedmeasurements. For example, a sense line may be connected to an amplifierso that a value associated with the capacitance of the sense line may beamplified and detected. From this directly measured value (e.g.,voltage, current, time, or any suitable value), a capacitance value maybe determined. This capacitance value may then be compared to thecapacitance value when the object is not presence, and the differencebetween these values may be measured as the delta capacitance. Since thevalues may depend on parameters of certain components (e.g., the amountof voltage applied to the drive line, the amount of time that the driveline is charged, the gain of the signal amplifier, or other parameters),other embodiments may experience different delta capacitance values.Furthermore, other embodiments may calculate the change in capacitancein any suitable manner.

Measurements 42 a and 42 b represent delta capacitance measurementstaken as an object moves across certain prior art touch sensors.Measurements 42 a and 42 b are shown to illustrate a technical advantageof certain embodiments of the present disclosure over certainalternative touch sensors. Measurement 40 a represents the measurementtaken by a capacitive node that has a different configuration from butis comparable in size to capacitive node 34 a of FIG. 5A. Measurement 40b represents the measurement taken by a capacitive node that has adifferent configuration from but is comparable in size to capacitivenode 34 b of FIG. 5A. In the illustrated embodiment, this change incapacitance is shown as a ratio of amplified measurements. Since thevalues may depend on parameters of certain components (e.g., the amountof voltage applied to the drive line, the amount of time that the driveline is charged, the gain of the signal amplifier, or other parameters),other embodiments may experience different delta values. Furthermore,other embodiments may calculate the change in capacitance in anysuitable manner.

Positions 44 a-44 e represent particular positions of the objectcorresponding to touch points 36 a-36 e, respectively, of FIG. 5A. Thedelta capacitance measurements at positions 44 b and 44 d are maximumdeltas, while the delta capacitance measurements at positions 44 a, 44c, and 44 e are minimum deltas. While delta capacitance at positions 44b and 44 d may be the same for measurements 40 a and 42 a and formeasurements 40 b and 42 b, delta capacitance at positions 44 a, 44 c,and 44 e may be greater for measurements 40 a and 40 b than formeasurements 42 a and 42 b. Thus, while certain embodiments may producethe same maximum delta as certain prior art touch sensors, certainembodiments may produce greater minimum deltas, thereby reducing thedifference between the maximum and minimum deltas, which may improvetouch sensor precision and/or linearity.

Threshold values 46 a and 46 b represent values set by certaintouch-sensor controllers as a threshold to register a delta capacitanceas a touch (or other presence) of the object. Threshold value 46 arepresents a threshold value for certain embodiments of the presentdisclosure that produce measurements 40 a and 40 b, while thresholdvalue 46 b represents a threshold value for certain prior art touchsensors that produce measurements 42 a and 42 b. For touch-sensorcontroller 12 to identify touches at the minimum sensitivity points oftouch sensor 10, threshold value 46 may need to be set below the minimumdelta value. Thus, increasing the minimum delta may allow thresholdvalue 46 to be increased, which may improve touch sensor precisionand/or linearity as explained further below with respect to FIG. 5C.

FIG. 5C illustrates a graph of example measurements and noise effectsthat may be measured by certain embodiments of touch sensor 10. Thisgraph includes measurements 40 a, 40 b, 42 a, and 42 b; threshold values46 a and 46 b; and noise effects 48. As discussed above with respect toFIG. 5B, measurements 40 a and 40 b represent delta capacitancemeasurements of certain embodiments of touch sensor 10, whilemeasurements 42 a and 42 b represent delta capacitance measurements ofcertain prior art touch sensors.

Noise effects 48 represent noise interference when performingtouch-sensing methods. The amount of noise effects 48 may be dependentupon the particular environment in which touch sensor 10 is located.Noise interference may adversely affect the precision and/or linearityof touch-sensing operations. For example, if noise effect 48 happens tobe above threshold value 46, touch-sensor controller 12 may not be ableto distinguish between noise and an actual touch by the object. Raisingthreshold value 46 may therefore reduce the negative impact of noiseinterference on the accurate detection of touches. Thus, since certainembodiments may increase the minimum delta, thereby allowing thresholdvalue 46 to be increased, such embodiments may reduce the occurrence offalse positives. As another example, noise interference may preventdetection of legitimate touches by causing a delta capacitancemeasurement that would otherwise register as a touch to drop below athreshold value. Thus, by increasing minimum delta capacitancemeasurements, certain embodiments may reduce the number of falsenegatives where the delta capacitance measurement falls below athreshold value due to noise effects 48.

FIG. 6A illustrates example test drawings 50 that may be registered bycertain embodiments of touch sensor 10. Similarly, FIG. 6B illustratesexample test drawings 52 that may be registered by certain prior arttouch sensors, such as those that might produce measurements 42 a and 42b of FIGS. 5B and 5C. Test drawings 50 and 52 represent the output oftouch-sensing operations resulting from identical touch inputs by anobject (e.g., a stylus). As discussed above, certain embodiments of thepresent disclosure may provide improved touch-sensing linearity. Suchtechnical advantages are illustrated by the improved precision andlinearity of the lines of test drawings 50 compared to test drawings 52.

Herein, “or” is inclusive and not exclusive, unless expressly indicatedotherwise or indicated otherwise by context. Therefore, herein, “A or B”means “A, B, or both,” unless expressly indicated otherwise or indicatedotherwise by context. Moreover, “and” is both joint and several, unlessexpressly indicated otherwise or indicated otherwise by context.Therefore, herein, “A and B” means “A and B, jointly or severally,”unless expressly indicated otherwise or indicated otherwise by context.

This disclosure encompasses all changes, substitutions, variations,alterations, and modifications to the example embodiments herein that aperson having ordinary skill in the art would comprehend. For example,while the embodiments of FIGS. 2, 3A-3B, 4, and 5A illustrate particularconfigurations of electrodes 22 and 24, any suitable number, type, andconfiguration may be used. As another example, while in certainembodiments electrodes 22 and 24 may be disposed on the same substrateor layer, other embodiments may have electrode 22 and 24 disposed onseparate substrates or layers. As yet another example, while thisdisclosure describes certain touch-sensing operations that may beperformed using the components of touch sensor 10 and touch-sensorcontroller 12, any suitable touch-sensing operations may be performed.

Moreover, although this disclosure describes and illustrates respectiveembodiments herein as including particular components, elements,functions, operations, or steps, any of these embodiments may includeany combination or permutation of any of the components, elements,functions, operations, or steps described or illustrated anywhere hereinthat a person having ordinary skill in the art would comprehend.Furthermore, reference in the appended claims to an apparatus or systemor a component of an apparatus or system being adapted to, arranged to,capable of, configured to, enabled to, operable to, or operative toperform a particular function encompasses that apparatus, system,component, whether or not it or that particular function is activated,turned on, or unlocked, as long as that apparatus, system, or componentis so adapted, arranged, capable, configured, enabled, operable, oroperative.

What is claimed is:
 1. A touch sensor comprising: a first electrodetrack comprising a first electrode, the first electrode comprising afirst segment, a second segment connected to the first segment, and athird segment connected to the first segment; a second electrode trackcomprising a second electrode comprising a fourth segment, a fifthsegment connected to the fourth segment, and a sixth segment connectedto the fourth segment, a portion of the second segment extending betweenportions of the fifth and sixth segments from the perspective orthogonalto a surface of the touch sensor, a portion of the fifth segmentextending between portions of the second and third segments from theperspective orthogonal to the surface of the touch sensor; a thirdelectrode track comprising a third electrode, a continuousdistinguishable portion of the third electrode positioned within, from aperspective orthogonal to the surface of the touch sensor, a gap formedbetween the second and third segments of the first electrode and thefifth and sixth segments of the second electrode such that thecontinuous distinguishable portion of the third electrode extends, inthe gap and from the perspective orthogonal to the surface of the touchsensor, between, and without overlapping in plan view from theperspective orthogonal to the surface of the touch sensor, the thirdsegment of the first electrode and the fifth segment of the secondelectrode, the second segment of the first electrode and the fifthsegment of the second electrode, and the second segment of the firstelectrode and the sixth segment of the second electrode; and respectivegaps, in plan view from the perspective orthogonal to the surface of thetouch sensor, between the continuous distinguishable portion of thethird electrode and the first segment of the first electrode, the secondsegment of the first electrode, the third segment of the firstelectrode, the fourth segment of the second electrode, the fifth segmentof the second electrode, and the sixth segment of the second electrode;wherein: the third electrode track surrounds the first electrode fromthe perspective orthogonal to the surface of the touch sensor; and thethird electrode track surrounds the second electrode from theperspective orthogonal to the surface of the touch sensor.
 2. The touchsensor of claim 1, wherein a portion of the third electrode track issubstantially perpendicular to the first and fourth segments.
 3. Thetouch sensor of claim 1, wherein: the touch sensor is configured tooperate as a mutual capacitance sensor; the first and second electrodetracks are configured to operate as drive lines of the touch sensor whenthe third electrode track is configured to operate as a sense line ofthe touch sensor.
 4. The touch sensor of claim 1, wherein: the touchsensor is configured to operate as a mutual capacitance sensor; thefirst and second electrode tracks are configured to operate as senselines of the touch sensor when the third electrode track is configuredto operate as a drive line of the touch sensor.
 5. The touch sensor ofclaim 1, wherein: the first and fourth segments are substantiallyparallel; the second, third, fifth, and sixth segments are substantiallyparallel; and the first and second segments are substantiallyperpendicular.
 6. The touch sensor of claim 1, wherein: the firstelectrode is formed approximately in the shape of a capital F; and thesecond electrode is formed approximately in the shape of an invertedcapital F.
 7. The touch sensor of claim 1, wherein: the first andsecond, and third segments lie substantially within a plane.
 8. Thetouch sensor of claim 1, wherein: the first electrode track furthercomprises: a fourth electrode comprising a seventh segment, an eighthsegment connected to the seventh segment, and a ninth segment connectedto the seventh segment; and a first conductive bridge galvanicallyconnecting the first and fourth electrodes; the second electrode trackfurther comprises: a fifth electrode comprising a tenth segment, aneleventh segment connected to the tenth segment, and a twelfth segmentconnected to the tenth segment; and a second conductive bridgegalvanically connecting the second and fifth electrodes; and the touchsensor further comprises a fourth electrode track comprising a sixthelectrode, a portion of the sixth electrode extending between portionsof the fourth and fifth electrodes from the perspective orthogonal tothe surface of the touch sensor; a portion of the eighth segment extendsbetween portions of the eleventh and twelfth segments from theperspective orthogonal to the surface of the touch sensor; and a portionof the eleventh segment extends between portions of the eighth and ninthsegments from the perspective orthogonal to the surface of the touchsensor.
 9. The touch sensor of claim 1, further comprising a substrate,wherein the first, second, and third electrodes are disposed on thesubstrate.
 10. The touch sensor of claim 1, further comprising first andsecond substrates, wherein the first and second electrodes are disposedon the first substrate, and the third electrode is disposed on thesecond substrate.
 11. An apparatus comprising: a touch sensorcomprising: a first electrode track comprising a first electrode, thefirst electrode comprising a first segment, a second segment connectedto the first segment, and a third segment connected to the firstsegment; a second electrode track comprising a second electrodecomprising a fourth segment, a fifth segment connected to the fourthsegment, and a sixth segment connected to the fourth segment, a portionof the second segment extending between portions of the fifth and sixthsegments from the perspective orthogonal to a surface of the touchsensor, a portion of the fifth segment extending between portions of thesecond and third segments from the perspective orthogonal to the surfaceof the touch sensor; a third electrode track comprising a thirdelectrode, a continuous distinguishable portion of the third electrodepositioned within, from a perspective orthogonal to the surface of thetouch sensor, a gap formed between the second and third segments of thefirst electrode and the fifth and sixth segments of the second electrodesuch that the continuous distinguishable portion of the third electrodeextends, in the gap and from the perspective orthogonal to the surfaceof the touch sensor, between, and without overlapping in plan view fromthe perspective orthogonal to the surface of the touch sensor, the thirdsegment of the first electrode and the fifth segment of the secondelectrode, the second segment of the first electrode and the fifthsegment of the second electrode, and the second segment of the firstelectrode and the sixth segment of the second electrode; and respectivegaps, in plan view from the perspective orthogonal to the surface of thetouch sensor, between the continuous distinguishable portion of thethird electrode and the first segment of the first electrode, the secondsegment of the first electrode, the third segment of the firstelectrode, the fourth segment of the second electrode, the fifth segmentof the second electrode, and the sixth segment of the second electrode;wherein: the third electrode track surrounds the first electrode fromthe perspective orthogonal to the plane; and the third electrode tracksurrounds the second electrode from the perspective orthogonal to theplane; and a controller configured to: apply voltage to a portion of thetouch sensor; measure a value associated with a portion of the touchsensor; determine a position of an object relative to the touch sensorbased at least on the value.
 12. The apparatus of claim 11, wherein aportion of the third electrode track is substantially perpendicular tothe first and fourth segments.
 13. The apparatus of claim 11, wherein:the touch sensor is configured to operate as a mutual capacitancesensor; the first and second electrode tracks are configured to operateas drive lines of the touch sensor when the third electrode track isconfigured to operate as a sense line of the touch sensor.
 14. Theapparatus of claim 11, wherein: the touch sensor is configured tooperate as a mutual capacitance sensor; the first and second electrodetracks are configured to operate as sense lines of the touch sensor whenthe third electrode track is configured to operate as a drive line ofthe touch sensor.
 15. The apparatus of claim 11, wherein: the first andfourth segments are substantially parallel; the second, third, fifth,and sixth segments are substantially parallel; and the first and secondsegments are substantially perpendicular.
 16. The apparatus of claim 11,wherein: the first electrode is formed approximately in the shape of acapital F; and the second electrode is formed approximately in the shapeof an inverted capital F.
 17. The apparatus of claim 11, wherein: thefirst and second, and third segments lie substantially within a plane.18. The apparatus of claim 11, wherein: the first electrode trackfurther comprises: a fourth electrode comprising a seventh segment, aneighth segment connected to the seventh segment, and a ninth segmentconnected to the seventh segment; and a first conductive bridgegalvanically connecting the first and fourth electrodes; the secondelectrode track further comprises: a fifth electrode comprising a tenthsegment, an eleventh segment connected to the tenth segment, and atwelfth segment connected to the tenth segment; and a second conductivebridge galvanically connecting the second and fifth electrodes; and thetouch sensor further comprises a fourth electrode track comprising asixth electrode, a portion of the sixth electrode extending betweenportions of the fourth and fifth electrodes from the perspectiveorthogonal to the surface of the touch sensor; a portion of the eighthsegment extends between portions of the eleventh and twelfth segmentsfrom the perspective orthogonal to the surface of the touch sensor; anda portion of the eleventh segment extends between portions of the eighthand ninth segments from the perspective orthogonal to the surface of thetouch sensor.
 19. A device comprising: a touch sensor comprising: afirst electrode track comprising a first electrode, the first electrodecomprising a first segment, a second segment connected to the firstsegment, and a third segment connected to the first segment; a secondelectrode track comprising a second electrode comprising a fourthsegment, a fifth segment connected to the fourth segment, and a sixthsegment connected to the fourth segment, a portion of the second segmentextending between portions of the fifth and sixth segments from theperspective orthogonal to a surface of the touch sensor, a portion ofthe fifth segment extending between portions of the second and thirdsegments from the perspective orthogonal to the surface of the touchsensor; a third electrode track comprising a third electrode, acontinuous distinguishable portion of the third electrode positionedwithin, from a perspective orthogonal to the surface of the touchsensor, a gap formed between the second and third segments of the firstelectrode and the fifth and sixth segments of the second electrode suchthat the continuous distinguishable portion of the third electrodeextends, in the gap and from the perspective orthogonal to the surfaceof the touch sensor, between, and without overlapping in plan view fromthe perspective orthogonal to the surface of the touch sensor, the thirdsegment of the first electrode and the fifth segment of the secondelectrode, the second segment of the first electrode and the fifthsegment of the second electrode, and the second segment of the firstelectrode and the sixth segment of the second electrode; and respectivegaps, in plan view from the perspective orthogonal to the surface of thetouch sensor, between the continuous distinguishable portion of thethird electrode and the first segment of the first electrode, the secondsegment of the first electrode, the third segment of the firstelectrode, the fourth segment of the second electrode, the fifth segmentof the second electrode, and the sixth segment of the second electrode;wherein: the third electrode track surrounds the first electrode fromthe perspective orthogonal to the plane; and the third electrode tracksurrounds the second electrode from the perspective orthogonal to theplane; a controller configured to: apply voltage to a portion of thetouch sensor; measure a value associated with a portion of the touchsensor; and determine a position of an object relative to the touchsensor based at least on the value; and a display overlaid by at least aportion of the touch sensor.